Controlling of the electronic properties of WS2 and graphene oxide heterostructures from first-principles calculations

Two-dimensional nanomaterials have attracted extensive interest and their heterostructures possess excellent electronic and optical properties suitable for various applications. Based on first-principles calculations, we investigated the structural stability and electronic properties of WS2 and graphene oxide (GO) heterostructures. We considered three types of GO, including epoxy only, hydroxyl only and both epoxy and hydroxyl on the GO surface. Our results show that the interlayer binding energy per WS2 unit increases from 0.117 eV to 0.214 eV as the surface oxygen concentration of GO increases. The band gap of the WS2/GO heterostructures can be efficiently tuned in a wide range from 0.13 eV to 1.91 eV by changing the oxygen functionalities and the concentration. The spatial separation of the conduction band minimum and valence band maximum is observed, which are distributed in different layers. In addition, the work function of WS2 can also be modulated by GO in the range of 4.09 eV to 6.34 eV, which potentially increases the carrier concentration and broadens the applications of WS2 and other transition metal dichalcogenide materials in optoelectronic devices.